The Yen’s rescue had almost nothing to do with the Treasury

The Yen has pulled itself up roughly 6% since late July, and market operations paid for nearly none of it. The US jointly intervened once, on July 31, and weekly reserve reporting data puts the size of that operation at around $500 million, well below the multi-billion-dollar operation Treasury Secretary Scott Bessent ‘leaked’ to markets with a badly positioned note on a napkin.

Everything the currency has done since then belongs entirely to the Bank of Japan (BoJ). Markets now expect the BoJ to raise its policy rate on September 18 to a level Japan has not seen in three decades. The Treasury promised a defence it has not paid for, and the Federal Reserve (Fed) facility it asked to have enlarged so that Japan could pay for one has still never been drawn. Two trades are currently long the Yen, the intervention trade and the rate trade. Both look identical on a screen, but only one of them has money behind it.

One shot, fired in July and spent by the end of August

The operation worked, briefly. USD/JPY had reached its weakest Yen level in about four decades when the New York Fed bought Yen on the Treasury's behalf through the Exchange Stabilization Fund (ESF), selling Euros to fund the purchase and executing through two primary dealers. It was the first joint Yen purchase by the two governments since 1998. The pair fell close to 157.00 inside the session before handing almost all of it back.

By August 28, USD/JPY was trading above 160.00 again. The operation's effect lasted four weeks. Intervention buys time rather than a level, and both capitals know it, so the question is what was built with the time. The answer on the record is nothing.

$500 million, and the figure has not moved since

Treasury has never disclosed what it spent. Senator Elizabeth Warren, Ranking Member on the Senate Banking Committee, asked for the figure on August 13, and Treasury Secretary Scott Bessent replied on August 27 without supplying it, or the execution rate, or the value of the position. The weekly US International Reserve Position supplies it anyway, indirectly. Strip out the effect of the Yen's own appreciation on the Dollar value of the holding and the ESF's Yen position leaves a residual of $505 million on August 7, $501 million on August 28, and $512 million on September 4. The variation across those weeks is valuation noise. The position has not been added to since it opened.

That window covers September 3, when the Yen gained more than 2% in a session, and the market decided authorities were back in the market. They were not. The move carries the signature of a rate check, which is the cheapest instrument in the drawer because it involves asking banks for a price rather than paying one. Set against Japan's own disclosed operation of ¥15.4 trillion between July 30 and August 26, close to $98 billion, the American contribution comes to roughly half of one percent.

The war chest is mostly a liability

The ESF's published balance sheet totals $217.028 billion, and that is the figure in circulation. Almost none of it can buy anything. Special drawing rights holdings of $172.062 billion sit against allocations of $156.482 billion and a further $15.2 billion of certificates issued to the Federal Reserve Banks, so the net position in the largest asset on the page comes to around $380 million. Net of liabilities the whole fund is worth $43.651 billion.

The part that can actually buy Yen is smaller again. US foreign currency reserves across Treasury and the Fed read $38.576 billion on September 4, of which $25.982 billion is Euros, which is what gets sold, and $12.594 billion is Yen, which is what gets bought. Japan spent close to four times the entire American Euro book in a single month. Treasury is not short of money in any sense that concerns a bond investor. It is short of this particular money, and topping it up requires Congress rather than a post.

The facility nobody has drawn, including the country that said it would

The FIMA repo facility is the intended answer to that constraint, and it was built for a different problem. Under the standing arrangement, the Desk offers overnight repo to foreign central banks against Treasury holdings in custody at the New York Fed, subject to a $60 billion limit per counterparty. The design brief was a dollar shortage: a central bank that needs dollars and would otherwise dump Treasuries to get them can pledge the paper instead and leave the Treasury market alone. Japan has no dollar shortage. It wants dollars to sell.

Usage tells the story the design does not. Since April 2020, the line has read exactly zero in 73.9% of weeks. The one genuine drawdown reached $60 billion in the week ending March 22, 2023, and was back at zero five weeks later, which means the facility's only real use in its life touched the per-counterparty ceiling to the decimal, during a banking crisis, on behalf of a borrower that was not Japan. Tokyo said in August that it planned to fund future intervention through the facility. The latest weekly release, covering the week ended September 9, shows $1 million.

Raising the cap does not need a vote of the Federal Open Market Committee (FOMC), whatever has been written to the contrary. Under the FOMC's rules of organisation the Foreign Currency Subcommittee comprises the Committee's Chair and Vice Chair and the Vice Chair of the Board, and it may change the rate, the maturity, the eligible counterparties and the counterparty limit on its own authority, informing the Committee afterwards. Three people can move this without a meeting, minutes or an announcement. Six weeks after Bessent made the request in public, they have not.

Tokyo funded the defence by selling what the facility exists to protect

Japan's own numbers show where the money came from. Foreign reserves fell $79.6 billion in August to $1.208 trillion, the steepest monthly decline since the series began in 2000, and foreign securities inside those reserves fell $87.8 billion. The facility built so that Japan would not have to sell Treasuries sat available and untouched through the month Japan sold Treasuries.

The selling also predates the emergency it is supposed to answer. Treasury International Capital (TIC) data has Japan's holdings at $1,116.7 billion in June against a February peak of $1,239.3 billion, a fall of $122.6 billion, and June is the most recent month published. The run began five months before the first Yen was bought. A different figure near $1.37 trillion circulates on a wider basis that folds in pension assets; the series quoted here is TIC, which counts custodial holdings.

The price this was all meant to protect never moved

The stated reason for routing Japan's intervention through a Fed facility was to keep Japanese selling out of the Treasury market and away from US borrowing costs. The 30-year yield was 5.28% on September 9, inside a range of 4.97%-5.31% since the start of July. It sat near the top of that range while the Yen rallied 6%, while Japan sold $87.8 billion of foreign securities, and while the facility went unused. The long end never noticed any of it.

What the Yen trade is actually long

Price sits near 154.00, close to ten Yen off the late-July high, which is more ground than the July operation took and it was taken without one. Momentum on the daily chart was overbought going into the September break and has unwound to the middle of its range since, so the move reads as having room rather than exhaustion behind it. The pattern is a lower high beneath 160.00 and a base forming above 152.00, with price below both the 50 and 200 EMA. The 200 EMA near 158.00 is the level that changes the reading.

The lean is short USD/JPY while the pair holds under 158.00, on the understanding that the position is a BoJ position wearing an intervention label. A daily close back above 158.00 is the invalidation and would say the hike has been paid for in advance. Below 152.00 the September leg extends and the intervention premium goes to nothing, because at that point no part of the price requires Washington to explain it.

The larger risk is that the rate story reverses. Futures put the Fed's September 16 hike near 90%. By December 9, a second increase is priced as nearly a sure thing, and a third reaches above 95% by March 2027. The BoJ moves two days after the Fed with a quarter point close to fully priced, which makes it the meeting that can disappoint rather than surprise. Both central banks are tightening and the market has the Fed tightening further and for longer, so the gap that actually drives this pair is priced to widen while the Yen rallies on the assumption that it narrows.

The Subcommittee can raise the cap on any day it chooses without telling anyone first, and the place it would surface is a Thursday statistical release rather than a press conference. It is the one branch that puts Washington back into the price, and the only one without a date.